Network selection and random access method and apparatus of machine-type communication user equipment in mobile communication system

ABSTRACT

A network selection, a random access method, and an apparatus of a Machine Type Communication (MTC) User Equipment (UE) for use in a Long Term Evolution (LTE) are provided. A cell selection method of an MTC terminal of the present disclosure includes receiving a message from a base station forming a cell, determining whether the message includes an MTC supportability indicator, and barring, when the message includes no MTC supportability indicator, scanning a frequency used in communication with the base station during a determined period.

CROSS-REFERENCE TO RELATED APPLICATION(S)

This application is a continuation application of prior application Ser.No. 15/589,288, filed on May 8, 2017, which is a continuationapplication of prior application Ser. No. 14/662,812, filed on Mar. 19,2015, which was issued as U.S. Pat. No. 9,648,445 on May 9, 2017 and wasbased on and claimed priority under 35 U.S.C. § 119(a) of a Koreanpatent application filed on Mar. 19, 2014 in the Korean IntellectualProperty Office and assigned Serial number 10-2014-0032172, the entiredisclosure of which is hereby incorporated by reference.

TECHNICAL FIELD

The present disclosure relates to a mobile communication system. Moreparticularly, the present disclosure relates to a network selection andrandom access method and apparatus of a Machine Type Communication (MTC)User Equipment (UE) in a Long Term Evolution (LTE) system.

BACKGROUND

With the rapid advance of communication technology, mobile communicationsystems have evolved to a 4th Generation (4G) communication systemsrepresented by Long Term Evolution (LTE) standardized 3rd GenerationPartnership Project (3GPP).

To meet the demand for wireless data traffic having increased sincedeployment of 4G communication systems, efforts have been made todevelop an improved 5G or pre-5G communication system. Therefore, the 5Gor pre-5G communication system is also called a ‘Beyond 4G Network’ or a‘Post LTE System’. The 5G communication system is considered to beimplemented in higher frequency (mmWave) bands, e.g., 60 GHz bands, soas to accomplish higher data rates. To decrease propagation loss of theradio waves and increase the transmission distance, the beamforming,massive multiple-input multiple-output (MIMO), Full Dimensional MIMO(FD-MIMO), array antenna, an analog beam forming, large scale antennatechniques are discussed in 5G communication systems. In addition, in 5Gcommunication systems, development for system network improvement isunder way based on advanced small cells, cloud Radio Access Networks(RANs), ultra-dense networks, device-to-device (D2D) communication,wireless backhaul, moving network, cooperative communication,Coordinated Multi-Points (CoMP), reception-end interference cancellationand the like. In the 5G system, Hybrid FSK and QAM Modulation (FQAM) andsliding window superposition coding (SWSC) as an advanced codingmodulation (ACM), and filter bank multi carrier (FBMC), non-orthogonalmultiple access (NOMA), and sparse code multiple access (SCMA) as anadvanced access technology have been developed.

The Internet, which is a human centered connectivity network wherehumans generate and consume information, is now evolving to the Internetof Things (IoT) where distributed entities, such as things, exchange andprocess information without human intervention. The Internet ofEverything (IoE), which is a combination of the IoT technology and theBig Data processing technology through connection with a cloud server,has emerged. As technology elements, such as “sensing technology”,“wired/wireless communication and network infrastructure”, “serviceinterface technology”, and “Security technology” have been demanded forIoT implementation, a sensor network, a Machine-to-Machine (M2M)communication, Machine Type Communication (MTC), and so forth have beenrecently researched. Such an IoT environment may provide intelligentInternet technology services that create a new value to human life bycollecting and analyzing data generated among connected things. IoT maybe applied to a variety of fields including smart home, smart building,smart city, smart car or connected cars, smart grid, health care, smartappliances and advanced medical services through convergence andcombination between existing Information Technology (IT) and variousindustrial applications.

In line with this, various attempts have been made to apply 5Gcommunication systems to IoT networks. For example, technologies such asa sensor network, Machine Type Communication (MTC), andMachine-to-Machine (M2M) communication may be implemented bybeamforming, MIMO, and array antennas. Application of a cloud RadioAccess Network (RAN) as the above-described Big Data processingtechnology may also be considered to be as an example of convergencebetween the 5G technology and the IoT technology.

The LTE system adopts technologies for supporting various types of UserEquipment (UE) including Machine Type Communication (MTC) UE. The MTC UEmay be a device, such as an electricity meter and water meter, which iscapable of metering consumption of a utility item and reporting the dataresult automatically and is characterized by low network accesspriority.

Typically, such an MTC UE configured for the purpose of metering doesnot need a high data transmission capability and is likely to have lowtransmit power and be installed in a place such as such as basement andwarehouse. There is therefore a need of assorting a UE categoryrequiring coverage expansion function to overcome the low transmit powerwhile operating at a low data rate. For this purpose, new UE category 0is added in addition to the legacy UE categories in LTE release 12 (thelarger the release number, the more recent the version is). The category0 UE is characterized by the low data rate (e.g., 1 Megabit(s) persecond (Mbps)) and may adopt supplementary transmission schemes tosecure relatively broad coverage at the low transmit power level. Thesupplementary transmission schemes may include repetitive transmissionscheme.

In order for the network support the supplementary transmission schemeof the UE, the UE has to connect to the evolved Node B (eNB) supportingthe corresponding transmission scheme. Also, the UE has to notify thenetwork that the UE is the MTC UE as soon as possible after beingconnected to the eNB such that the network is capable of recognizing theconnection of the MTC UE and applying the supplementary transmissionscheme to the MTC UE immediately to maintain a connection stably.

The above information is presented as background information only toassist with an understanding of the present disclosure. No determinationhas been made, and no assertion is made, as to whether any of the abovemight be applicable as prior art with regard to the present disclosure.

SUMMARY

Aspects of the present disclosure are to address at least theabove-mentioned problems and/or disadvantages and to provide at leastthe advantages described below. Accordingly, an aspect of the presentdisclosure is to provide an evolved Node B (eNB)/cell (re)selectionmethod of a Machine Type Communication (MTC) User Equipment (UE) that iscapable of allowing the MTC UE to connect the eNB supporting the eNB'sUE class with priority and notifying the network of the eNB's MTC UEclass as soon as possible.

In accordance with an aspect of the present disclosure, a cell selectionmethod of a category 0 UE (an MTC terminal) is provided. The cellselection method includes receiving a message from a base stationforming a cell, determining whether the message includes allowanceinformation regarding an access of the category 0 UE to the cell, andbarring, when the message does not include the allowance information, aselection of the cell.

In accordance with another aspect of the present disclosure, a category0 UE is provided. The category 0 UE includes a transceiver configured totransmit and receive signals to and from a base station forming a celland a controller configured to determine whether a message received fromthe base station includes allowance information regarding an access ofthe category 0 UE to the cell, and to bar, when the message does notinclude the allowance information, a selection of the cell.

In accordance with another aspect of the present disclosure, a messagetransmission method of a base station is provided. The messagetransmission method includes determining whether the base station allowsan access of a category 0 UE to a cell formed by the base station,generating, when the base station allows the access of the category 0 UEto the cell, a message including allowance information regarding theaccess of the category 0 UE to the cell, and transmitting the message toa terminal.

In accordance with another aspect of the present disclosure, a basestation is provided. The base station includes a transceiver configuredto transmit and receive signals to and from a terminal and a controllerconfigured to determine whether the base station allows an access of acategory 0 User Equipment (UE) to a cell formed by the base station, togenerate, when the base station allows the access of the category 0 UEto the cell, a message including allowance information regarding theaccess of the category 0 UE to the cell, and to transmit the message tothe terminal.

In accordance with another aspect of the present disclosure, a randomaccess method of a category 0 UE is provided. The random access methodincludes transmitting, when a Random Access Response (RAR) message isreceived from a base station, a connection setup request message to thebase station and receiving a connection setup message in response to theconnection setup request message. The connection setup request messageincludes a category 0 UE indication information.

In accordance with another aspect of the present disclosure, a category0 UE is provided. The category 0 UE includes a transceiver configured totransmit and receive to and from a base station and a controllerconfigured to control the transceiver to transmit, when a RAR message isreceived from a base station, a connection setup request message to thebase station and to receive a connection setup message in response tothe connection setup request message. The connection setup requestmessage includes terminal category 0 UE indication information.

In accordance with another aspect of the present disclosure, a method ofperforming, at a base station, a random access procedure with terminalcategory 0 UE is provided. The method includes receiving a connectionsetup request message from a terminal, determining whether the terminalis the category 0 UE based on the received connection setup requestmessage, determining whether a size of a connection setup message to betransmitted to the category 0 UE is greater than a message size allowedfor the category 0 UE, and transmitting, when the size of the connectionsetup message is greater than the message size allowed for the category0 UE, to the category 0 UE the connection message as fragmented orrepeated.

In accordance with another aspect of the present disclosure, a basestation is provided. The base station includes a transceiver configuredto transmit and receive signals to and from a terminal and a controllerconfigured to control the transceiver to receive a connection setuprequest message from a terminal, to determine whether the terminal isthe category 0 UE based on the received connection setup requestmessage, to determine whether a size of a connection setup message to betransmitted to the category 0 UE is greater than a message size allowedfor the category 0 UE, and to transmit, when the size of the connectionsetup message is greater than the message size allowed for the category0 UE, to the category 0 UE the connection message as fragmented orrepeated.

Other aspects, advantages, and salient features of the disclosure willbecome apparent to those skilled in the art from the following detaileddescription, which, taken in conjunction with the annexed drawings,discloses various embodiments of the present disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other aspects, features, and advantages of certainembodiments of the present disclosure will be more apparent from thefollowing description taken in conjunction with the accompanyingdrawings, in which:

FIG. 1 is a diagram illustrating an architecture of a Long TermEvolution (LTE) system according to an embodiment of the presentdisclosure;

FIG. 2 is a diagram illustrating a protocol stack of an LTE systemaccording to an embodiment of the present disclosure;

FIG. 3 is a signal flow diagram illustrating a cell selection method ofa Machine Type Communication (MTC) User Equipment (UE) according to anembodiment of the present disclosure;

FIG. 4 is a signal flow diagram illustrating a cell selection method ofan MTC UE according to an embodiment of the present disclosure;

FIG. 5 is a flowchart illustrating a cell selection method of an MTC UEaccording to an embodiment of the present disclosure;

FIG. 6 is a flowchart illustrating an evolved Node B (eNB)-sideprocedure of a cell selection method according to an embodiment of thepresent disclosure;

FIG. 7 is a signal flow diagram illustrating a random access procedureof a MTC UE to an eNB supporting the MTC UE according to an embodimentof the present disclosure;

FIG. 8 is a flowchart illustrating a UE-side procedure of a randomaccess procedure to an eNB supporting an MTC UE according to anembodiment of the present disclosure;

FIG. 9 is a flowchart illustrating an eNB-side procedure of a randomaccess procedure to an eNB supporting an MTC UE according to anembodiment of the present disclosure;

FIG. 10 is block diagram illustrating a configuration of the UEaccording to an embodiment of the present disclosure; and

FIG. 11 is a block diagram illustrating a configuration of an eNBaccording to an embodiment of the present disclosure.

Throughout the drawings, it should be noted that like reference numbersare used to depict the same or similar elements, features, andstructures.

DETAILED DESCRIPTION

The following description with reference to the accompanying drawings isprovided to assist in a comprehensive understanding of variousembodiments of the present disclosure as defined by the claims and theirequivalents. It includes various specific details to assist in thatunderstanding but these are to be regarded as merely exemplary.Accordingly, those of ordinary skill in the art will recognize thatvarious changes and modifications of the various embodiments describedherein may be made without departing from the scope and spirit of thepresent disclosure. In addition, descriptions of well-known functionsand constructions may be omitted for clarity and conciseness.

The terms and words used in the following description and claims are notlimited to the bibliographical meanings, but, are merely used by theinventor to enable a clear and consistent understanding of the presentdisclosure. Accordingly, it should be apparent to those skilled in theart that the following description of various embodiments of the presentdisclosure is provided for illustration purpose only and not for thepurpose of limiting the present disclosure as defined by the appendedclaims and their equivalents.

It is to be understood that the singular forms “a,” “an,” and “the”include plural referents unless the context clearly dictates otherwise.Thus, for example, reference to “a component surface” includes referenceto one or more of such surfaces.

The present disclosure proposes the following methods in order for aMachine Type Communication (MTC) User Equipment (UE) to select anevolved Node B (eNB) supporting MTC UE.

The eNB transmits the eNB's MTC UE supportability using a broadcastmessage.

The broadcast message may be a determined System Information Block(SIB).

The UE scans eNBs per frequency and, if the eNB or cell having thestrongest signal on one frequency does not support MTC UE, bars theaccess on the frequency and reduces the priority of the correspondingfrequency in a determined duration. That is, although a cell havingstrong signal strength is found while scanning the correspondingfrequency supporting the UE for selection, the UE selects, if there isany cell found on another frequency, the cell operating on the anotherfrequency.

Also, the present disclosure proposes the following methods in order forthe MTC UE to notify the eNB that the MTC UE is a UE of a MTC UE typewhen the MTC UE attempts to connect the eNB.

The header of a message transmitted from the UE to the eNB in the randomaccess procedure includes a logical channel identifier (LCID) for use atthe eNB in determining whether the UE is an MTC UE.

The message transmitted from the UE to the eNB may be message 3 (Msg3)among the messages used in the random access procedure.

Upon receipt of the message including the LCID, the eNB determines thecorresponding UE as an MTC UE and then applies, to the communicationwith the corresponding UE, transmission message size adjustment (e.g.,fragmentation) and supplementary transmission scheme (e.g.,retransmission).

FIG. 1 is a diagram illustrating an architecture of a Long TermEvolution (LTE) system according to an embodiment of the presentdisclosure.

Referring to FIG. 1, a radio access network of the LTE system includeseNBs 105, 110, 115, and 120, a Mobility Management Entity (MME) 125, anda Serving-Gateway (S-GW) 130. A UE 135 connects to an external networkvia the eNBs 105, 110, 115, and 120 and the S-GW 130.

Referring to FIG. 1, the eNBs 105, 110, 115, and 120 correspond to thelegacy node Bs of the Universal Mobile Telecommunications System (UMTS).The eNBs 105, 110, 115, and 120 allow the UE 135 to establish a radiochannel and are responsible for functions more complicated as comparedto the legacy node B. In the LTE system, all the user traffic servicesincluding real time services such as Voice over Internet Protocol (VoIP)are provided through a shared channel and thus there is a need of adevice to schedule data based on the state information such as bufferstates, power headroom states, and channel states of the UEs, the eNBsbeing responsible for such functions. Typically, one eNB controls aplurality of cells. In order to secure the data rate of up to 100 Mbps,the LTE system adopts Orthogonal Frequency Division Multiplexing (OFDM)as a radio access technology. Also, the LTE system adopts AdaptiveModulation and Coding (AMC) to determine the modulation scheme andchannel coding rate in adaptation to the channel condition of the UE.The S-GW 130 is an entity to provide data bearers so as to establish andrelease data bearers under the control of the MME 125. The MME 125 isresponsible for mobility management of UEs and various control functionsand may be connected to a plurality of eNBs.

FIG. 2 is a diagram illustrating a protocol stack of an LTE systemaccording to an embodiment of the present disclosure.

Referring to FIG. 2, a protocol stack of the LTE system includes PacketData Convergence Protocol (PDCP) 205 and 240, Radio Link Control (RLC)210 and 235, Medium Access Control (MAC) 215 and 230, and Physical (PHY)220 and 225. The PDCPs 205 and 240 are responsible for IP headercompression/decompression, and the RLCs 210 and 235 are responsible forsegmenting the PDCP Protocol Data Unit (PDU) into segments inappropriate size for Automatic Repeat Request (ARQ) operation. The MACs215 and 230 are responsible for establishing connection to a pluralityof RLC entities so as to multiplex the RLC PDUs into MAC PDUs anddemultiplex the MAC PDUs into RLC PDUs. The PHYs 220 and 225 performschannel coding on the MAC PDU and modulates the MAC PDU into OFDMsymbols to transmit over radio channel or performs demodulating andchannel-decoding on the received OFDM symbols and delivers the decodeddata to the upper layer. Also, the PHY layer uses Hybrid ARQ (HARQ) foradditional error correction by transmitting 1 bit information indicatingfor positive or negative acknowledgement from the receiver to thetransmitter. This is referred to as HARQ ACK/NACK information. Thedownlink HARQ ACK/NACK corresponding to the uplink transmission iscarried by Physical Hybrid-ARQ Indicator Channel (PHICH), and the uplinkHARQ ACK/NACK corresponding to downlink transmission is carried byPhysical Uplink Control Channel (PUCCH) or Physical Uplink SharedChannel (PUSCH).

FIG. 3 is a signal flow diagram illustrating a cell selection method ofan MTC UE according to an embodiment of the present disclosure.

Referring to FIG. 3, a UE 301 powers on at operation 311 and initiates acell selection procedure to select a cell to camp on among theneighboring eNBs (or cells) 303 and 305 at operation 313.

For this purpose, the UE scans operating cells (frequencies) the UEsupports to discover cells. Herein, the terms “frequency” and “cell” areused interchangeably in the same meaning In FIG. 3, the UE scansfrequency 1 (f1) first at operation 321. After switching to thecorresponding frequency to scan the frequency 1, the UE 301 receives thesignals transmitted on the frequency 1. From the received signals, theUE 301 may extract synchronization signals 323 and messages 325 carryingsystem information. The message carrying the system information includesa plurality of SIBs that are sorted into SIB1, SIB2, SIB3, etc.according to the purpose and type of information.

The UE 301 selects an eNB 303 or 305 with the best received signalstrength among eNBs 303 and 305 transmitting the synchronization signalto acquire synchronization with the corresponding eNB at operation 323and receives messages (e.g., SIBs) from the eNB synchronized therewithat operation 325. According to an embodiment of the present disclosure,if the eNB 303 or 305 is supports the MTC UE (allows an access of theMTC UE to a cell formed by the eNB 303 or 305), the eNB 303 or 305 sendsthe MTC UE an indicator of notifying the UE 301 whether the eNB 303 or305 supports the MTC UE. The indicator may be 1-bit indicatortransmitted through one of the SIBs (e.g., SIB1 or an SIB definednewly). The indicator may be allowance information regarding an accessof the category 0 UE to the cell formed by the eNB 303 or 305.

The UE 301 establishes synchronization with the eNB 303 or 305 havingthe best signal strength and quality per frequency to determine the cellto camp on and monitors the SIBs to detect the indicator indicating ofthe MTC UE supportability through the neighboring cell scanning If thecorresponding eNB 303 or 305 does not support the MTC UE, the UE 301blocks scanning the corresponding frequency (bars to camp on the eNB)during a determined period at operation 327. That means that the eNB 303or 305 bars a selection of a cell if the eNB 303 or 305 does not allowsan access of MTC UE to the cell formed by the eNB 303 or 305. This is toprevent the MTC UE from staying in the coverage of the eNB 303 or 305,which does not support the MTC UE so as to avoid communication failureafterward. In order to accomplish this, a timer or counter may be used,and the length of the timer or the value of the counter may be set to avalue predefined in the standard or carried in the SIB messagetransmitted by the eNB 303 or 305 supporting MTC. For example, the eNB303 or 305 may broadcast the timer value for barring to camp on (e.g., 1minute) in the SIB 1 in order for the UEs located within the cell toreceive the timer value. If the timer value is received, the MTC UEstarts the timer when the cell having the best signal strength on aspecific frequency does not support MTC to reduce the cell selectionpriority of the corresponding frequency during the time corresponding tothe timer (1 minute in this embodiment of the present disclosure). Thetimer or counter may start when it is determined that the correspondingeNB 303 or 305 does not support MTC for the reason of reception failureof the MTC indicator. The UE 301 may bar the frequencies on which thecells supporting MTC operate after the completion of cell search or uponor after determining the frequency or cell to camp on.

After finding the eNB 303 or 305 having the best signal strength on thefrequency 1, the UE 301 switches the frequency to the frequency 2 (f2)to search for the eNB 303 or 305 having the best signal strength on thef2 at operation 331.

Like the operation on the f1, the UE 301 selects the eNB 303 or 305having the best signal strength among the eNBs 303 and 305 operating onthe ff2 to establish synchronization with the corresponding eNB atoperation 333 and receives the messages (e.g. SIBs) transmitted by thecorresponding eNB 303 or 305 at operation 335. It is assumed the eNB 303or 305 with which the synchronization is acquired on the ff2 is the eNB303 or 305 supporting MTC. As described above, the eNB 303 or 305 withwhich the synchronization is acquire on the ff2 may transmit the systeminformation block including the indicator notifying whether the eNB 303or 305 supports MTC. Although FIG. 3 is directed to the case where theUE 301 performs the procedure of receiving from the eNBs 303 and 305operating on two frequencies (f1 and f2), the present disclosure is notlimited thereto. For example, the UE may perform the above procedure on15 (f1 to f15) frequencies.

The UE 301 checks information on the cells having the best signalstrength on the respective frequencies, checks the MTC supportabilitiesof the cells, and determines the cell to camp thereon based on theoperator information and MTC cell supportabilities of the per-frequencycells at operation 337. As described above, if the non-MTC cells arebarred, the UE 301 may bar scanning the corresponding frequencies sincethe eNB 303 or 305 is determined as non-MTC eNB at operation 327, thebarring state may last until operation 337. Unlike this, the UE 301 maybar the frequencies on which the cells supporting MTC operate after thecompletion of cell scanning or upon or after determining the frequencyor cell to camp on.

FIG. 4 is a signal flow diagram illustrating a cell selection method ofan MTC UE according to an embodiment of the present disclosure.

Referring to FIG. 4, a UE 401 powers on at operation 411 and starts thecell selection procedure to select one of the cell among the neighboringcells (or eNBs) 403 and 405 at operation 413.

Since operations 421, 423, 425, 431, 433, 435, and 437 of FIG. 4 areidentical with operations 321, 323, 325, 331, 333, 335, and 337 of FIG.3, detailed descriptions thereof are omitted herein. Although FIG. 4 isdirected to the case where two frequencies are scanned, the presentdisclosure is not limited thereto.

Referring to FIG. 3, if it is determined that the corresponding eNB 403or 405 does not support MTC based on the message received from the eNB,e.g. since it is determined that the corresponding eNB 403 or 405 doesnot support the MTC UE, the corresponding frequency is barred during adetermined period. Unlike the embodiment of FIG. 4, the frequencies onwhich the non-MTC cells operate are barred after the completion of thecell search or upon the determination of the frequency or cell to campon or after a determined time lapses since the determination of thefrequency or cell to camp on at operation 439. FIG. 4 is directed to thecase whether the f1 is barred during a determined period. Assuming thatthe UE 401 supports 15 frequencies (f1 to f15) unlike the embodiment ofFIG. 4, the frequencies on which non-MTC cells operate (e.g. f1, f5, andf11) may be barred after the completion of the cell search on all of the15 frequencies.

FIG. 5 is a flowchart illustrating a cell selection method of an MTC UEaccording to an embodiment of the present disclosure.

Referring to FIG. 5, if the cell selection procedure starts, the UEdetermines whether the previous cell selection-related information isstored at operation 501. For example, if the UE has powered on and thenoff, the information used in the last connection may be stored in theUE's storage. If there is such information stored in the UE, the UEselects the frequencies based on the corresponding information andsearches for per-frequency best cells and receives information from thefound cells at operation 503. Otherwise if there is no such informationstored in the UE, the UE searches all frequencies for per-frequency bestcells and receives information from the found cells at operation 505.Afterward, the UE selects the frequencies having non-MTC cells among theper-frequency best cells at operation 507. In this way, the UE maydetermine whether there is any non-MTC frequency depending on whetherthe eNB transmits the MTC indicator at operation 509 as described withreference to FIG. 3. If there are one or more non-MTC frequencies, thecorresponding frequency (or frequencies) is barred during a determinedperiod such that the UE rules out the corresponding frequency (orfrequencies) in the cell selection procedure at operation 511. In orderto check the expiry of the determined period, a timer or counter may beused.

Afterward, the UE selects a cell to camp on among the per-frequencycells based on the operator information and MTC UE supportability atoperation 513 and ends the cell selection procedure at operation 515.

FIG. 6 is a flowchart illustrating an eNB-side procedure of a cellselection method according to an embodiment of the present disclosure.

Referring to FIG. 6, an eNB determines whether the eNB supports MTC UEat operation 601. If the eNB supports the MTC UE, the eNB generates asystem information block message including an MTC supportabilityindication information at operation 603. The MTC supportabilityindication information may include a 1-bit indicator indicating whetherthe eNB supports the MTC UE and information on the frequency barringtime or counter value optionally. If the eNB does not support MTC UE,the eNB generates the system information block message without MTCsupport indication information at operation 605. Next, the eNB transmitsthe generated system information block to the UE at operation 607.

FIG. 7 is a signal flow diagram illustrating a random access procedureof an MTC UE to an eNB supporting the MTC UE according to an embodimentof the present disclosure.

Referring to FIG. 7, it is assumed that a UE 701 is an MTC UE (category0 UE) and the eNB or cell 703 supports MTC.

Since the MTC UE operates with a low transmit power and a broad coverageand may transmit small size messages during a determined period, thereis a need of an MTC eNB to support the MTC UE. Meanwhile, the MTC eNBhas to support normal UEs as well as MTC UEs and distinguish between thenormal and MTC UEs based on the category information transmitted by theMTC UE. Category 0 is defined newly for the MTC UE and, if thecorresponding category information is received, the eNB determines thecorresponding UE as MTC UE and adopts a specific transmission scheme forthe MTC UE (which is different from that for normal UE) in order for theMTC UE to transmit small size message at a low transmit power.

According to the method of the related art, the category information istransmitted after the UE connects to the corresponding eNB successfullyso as to be in the connected mode. That is, if data communicationnecessity occurs in the idle mode, the UE initiates a random accessprocedure to enter the connected mode and, when the random accessprocedure is completed successfully, then it is possible for the UE totransmit the category information. Accordingly, the UE cannot identifywhether the corresponding UE is a normal UE or an MTC UE in the middleof the random access procedure and thus there is a need of negating thenecessity for transmitting the random access message in a specific way(e.g. repetitive transmission) or segmenting a large message into smallsize messages. The embodiment of FIG. 7 shows a procedure of solvingsuch a problem.

If data communication necessity occurs in the idle mode, the UE 701transmits a preamble (msg 1) to an eNB 703 to enter the connected modeat operation 711. The preamble may be the random access preamble whichis transmitted repeatedly by a normal UE or a preamble designed newlyfor supporting MTC UEs with wide coverage.

Upon receipt of the preamble, the eNB 703 sends the UE 701 a RAR message(Msg2) to acknowledge the receipt of the preamble at operation 713. TheRAR message includes preamble identity information and resourceallocation information in order for the UE 701, which has transmittedthe preamble to transmit additional message.

If the RAR message is received successfully, the UE 701 sends the eNB703 a Connection Setup Request message (Msg3) 715. The connection SetupRequest message is the Radio Resource Control (RRC) layer message suchas RRCConnectionRequest message specified in the 3rd GenerationPartnership Project (3GPP) standard. The UE 701 transmits the message onthe resource allocated by the eNB 703. The message is transmitted in theMAC Service Data Unit (SDU) of which MAC header includes a 5-bit LCIDallocated by the eNB 703. In the case of initial transmission, the UE701 has no LCID allocated by the eNB 703 yet and thus, if the UE 701 isthe normal UE, the UE 701 transmits the message using the identifier setto 00000. Table 1 shows LCID values for use in uplink. Beforetransitioning from the idle mode to the connected mode after completingthe random access procedure successfully, the UE 701 uses the identifierset to 00000 allocated for the Common Control Channel for transmittingcontrol message as shown in Table 1.

TABLE 1 Index (binary) LCID values 00000 Common Control Channel00001-01010 Identity of the logical channel 01011-11000 Reserved 11001Extended Power Headroom Report 11010 Power Headroom Report 11011 C-RNTI11100 Truncated BSR 11101 Short BSR 11110 Long BSR 11111 Padding

However, the present disclosure proposes a method of using a separatevalue instead of using the LCID 00000 when the UE 701 is an MTC UE. Theseparate value may be one of the binary values in the range from 01011to 11000 that are reserved currently. According to an embodiment of thepresent disclosure, the eNB 703 checks the LCID included in the message(Msg3) received at operation 715 to determine whether the correspondingUE 701 is a normal UE or an MTC UE. In this way, the eNB 703 may acquirethe UE 701 information before the end of the random access procedure toallocate resource to the corresponding UE 701 and communicate data withthe corresponding UE 701. In the case that the UE 701 is the MTC UE, thenumber of bits which the UE 701 may receive in one subframe (1millisecond) is limited (e.g. 1000 bits). If, although the size of themessage (Msg4) to be transmitted at operation 719 in response to theMsg3 is longer than 1000 bits, the eNB 703 transmits the data of whichsize is greater than 1000 bits, the UE 703 cannot receive the Msg4correctly.

According to an embodiment of the present disclosure, if it isdetermined that the UE 701 is the MTC UE based on the LCID of the UE 701at operation 715, the eNB 703 determines whether the size of the message(Msg4 in FIG. 7) to be transmitted is greater than the size allowed forthe MTC UE at operation 717. If the size of the corresponding message isgreater than the message size allowed for MTC UE, the eNB 703 mayfragment the message or removes part of the message content fortransmission at operation 719. The message may be the RRCConnectionSetupmessage. In this way, the UE 701 notifies the network that the UE 701 isthe MTC UE before the UE 701 notifies the network of the UE 701's MTCcapability so as to establish a connection with the eNB 703successfully.

FIG. 8 is a flowchart illustrating a UE-side procedure of a randomaccess procedure to an eNB supporting MTC UE according to an embodimentof the present disclosure.

Referring to FIG. 8, in the random access procedure, the UE transmits arandom access preamble to an eNB at operation 801. Afterwards, the UEreceives a RAR message in response to the random access preamble atoperation 803. As shown in FIG. 3 or 4, the eNB determines whether theeNB supports MTC based on the MTC supportability indicator at operation805. If the eNB does not support the MTC UE, the eNB transmits a messagehaving a MAC header including a legacy LCID value at operation 807. Ifthe eNB supports the MTC UE, the eNB transmits a message having the MACheader including a new LCID proposed in the present disclosure atoperation 809. Afterward, UE receives a message processed suitable forMTC UE (e.g. fragmented or repeated message) from the eNB at operation811 and ends the random access procedure at operation 813.

FIG. 9 is a flowchart illustrating an eNB-side procedure of a randomaccess procedure to the eNB supporting MTC UE according to an embodimentof the present disclosure.

Referring to FIG. 9, if a message is received on the allocated resource,an eNB determines whether the received message has a MAC headerincluding an LCID proposed newly in the present disclosure at operation901 and, if the received message includes the newly proposed LCID, theeNB determines the corresponding UE as the MTC UE at operation 903 anddetermines whether the size of the message (Msg4 in FIG. 7) to betransmitted is greater than the message size allowed for MTC UE. If thesize of the message is greater than the message allowed for MTC UE, theeNB fragment the corresponding message or removes part of the messagecontent for transmission at operation 905. In this way, the UE notifiesthe network of the UE category in advance before transmitting the UEcategory information so as to establish a connection with the eNBsuccessfully.

FIG. 10 is block diagram illustrating a configuration of the UEaccording to an embodiment of the present disclosure.

Referring to FIG. 10, a UE according to an embodiment of the presentdisclosure includes a transceiver 1005, a controller 1010, amultiplexer/demultiplexer 1020, a control message processor 1035, andupper layer processor 1025 and 1030.

The transceiver 1005 is responsible for receiving data and a determinedcontrol signal through a downlink channel of the serving cell andtransmitting data and determined control signals through an uplinkchannel In the case that a plurality of serving cells is configured, thetransceiver 1005 transmits and receives data and control signals throughthe plural serving cells.

The multiplexer/demultiplexer 1015 is responsible for multiplexing datagenerated by the upper layer processors 1020 and 1025 and the controlmessage processor 1035 or demultiplexing data received by thetransceiver 1005 to deliver the demultiplexed data to the upper layerprocessors 1025 and 1030 and the control message processor 1035.

The control message processor 1035 processes the control messagereceived from the eNB and takes a necessary action.

The upper layer processor 1025 and 1030 is established per service. Theupper layer processors 1025 and 1030 process the data generated in theuser service such as File Transfer Protocol (FPT) and VoIP and transfersthe processed data to the multiplexer/demultiplexer 1020 or processesthe data from the multiplexer/demultiplexer 1020 and delivers theprocessed data to the upper layer service applications.

The controller 1010 checks the scheduling command, e.g. uplink grants,received through the transceiver 1005 and controls the transceiver 1005and the multiplexer/demultiplexer 1020 to perform uplink transmissionwith appropriate transmission resource at an appropriate timing.

The control message processor 1035 controls such that the Msg3 messageincluding the newly proposed LCID value is transmitted in the randomaccess procedure when the UE is the MTC UE and thus the eNB is aware ofthe UE category before receiving the MTC UE notification message as anupper layer message.

Although the transceiver 1005, the controller 1010, themultiplexer/demultiplexer 1020, the control message processor 1035, andthe upper layer processor 1025 and 1030 are depicted as separate blocksresponsible for different functions in FIG. 10 for explanationconvenience, the configuration is not limited thereto. For example, if amessage is received from the eNB, the controller 1010 determines whetherthe message includes an MTC UE supportability indicator and, if no MTCUE supportability indicator is included, the UE bars the frequencies ofthe corresponding eNB for cell search during a determined period. Thismessage may be a broadcast message. The broadcast message may be a SIB.The controller 1010 may bar the corresponding frequency right after itis determined that the message has no MTC UE supportability indicator.The controller also may bar the corresponding frequency after thecompletion of cell search or upon or after a determined time since thedetermination of the frequency or cell to camp on. If the cell searchhas been completed on all the frequencies supported by the UE, thecontroller 1010 may select the cell to camp on based on the operatorinformation or MTC UE supportability.

If the RAR message is received from the eNB, the controller 1010controls to transmit to connection setup request message to the eNB andreceive a connection setup message from the eNB in response to the RARmessage. The connection setup request message may include an indicatornotifying that the UE is the MTC UE. The connection setup requestmessage may be the RRCConnectionRequest message. The indicator informingthat the UE is the MTC UE may be included in the MAC header of theconnection setup request message. The indicator informing that the UE isthe MTC UE may be LCID set to a value in the range from 0b01011 to0b11000. The connection setup message may be of being fragmented orrepeated.

FIG. 11 is a block diagram illustrating a configuration of an eNBaccording to an embodiment of the present disclosure.

Referring to FIG. 11, an eNB includes a transceiver 1105, a controller1110, a scheduler 1115, a multiplexer/demultiplexer 1120, a controlmessage processor 1135, upper layer processors 1125 and 1130.

The transceiver 1105 is responsible for transmitting data and adetermined control signal through a downlink channel and receiving dataand the determined control signals through an uplink channel. In thecase that a plurality of carriers is configured, the transceiver 1105transmits and receives data and control signals through the pluralcarriers.

The multiplexer/demultiplexer 1120 is responsible for multiplexing datagenerated by the upper layer processors 1125 and 1130 and the controlmessage processor 1135 or demultiplexing data received by thetransceiver 1105 to deliver the demultiplexed data to the upper layerprocessors 1125 and 1130, the control message processor 1135, and thecontroller 1110. The control message processor 1135 processes thecontrol message transmitted by the UE to take a necessary action orgenerates a control message addressed to the UE to the lower layer.

The upper layer processor 1125 (or 1130) is established per service,processes the data to be transmitted to the S-GW or another eNB into RLCPDU and transfers the RLC PDU to the multiplexer/demultiplexer 1120, andprocesses the RLC PDU from the multiplexer/demultiplexer 1120 into PDCPSDU to be transmitted to the S-GW or another eNB.

The controller 1110 controls the transceiver 1105 to receive the channelstate information transmitted by the UE.

The scheduler 1115 allocates transmission resource to the UE at anappropriate timing in consideration of the buffer state and channelcondition of the UE and processes the signal transmitted from the UE orto be transmitted to the UE by means of the transceiver 1105.

The control message processor 1135 transmits an SIB message includingthe MTC supportability indicator to the UE and, if a message including anewly proposed LCID is received from the UE, the eNB determines that thecorresponding UE is the MTC UE so as to transmit data in the manner ofbeing repeated or fragmented.

Although the transceiver 1105, the controller 1110, themultiplexer/demultiplexer 1120, the control message processor 1135, andthe upper layer processor 1025 and 1030 are depicted as separate blocksresponsible for different functions in FIG. 11 for explanationconvenience, the configuration is not limited thereto. For example, thecontroller 1110 may determine whether the eNB supports MTC UE and, ifso, generates a message including an indicator of whether the eNBsupports MTC UE, and transmits the message to the UE. This message maybe a broadcast message. The broadcast message may be a SIB.

The controller 1110 may receive a connection setup request message fromthe UE, determine whether the UE is an MTC UE, check whether the size ofthe connection setup message to be transmitted to the UE is greater thana determined size allowed for the UE to receive and, if so, transmit theconnection setup message in the manner of being repeated or fragmented.The MTC UE indication information may be included in the MAC header ofthe connection setup request message. The MTC UE indication informationmay be an LCID set to a value in the range from 0b01011 to 0b11000.

As described above, the network selection and random access method andapparatus of the present disclosure is advantageous in that the MTC UEselects the network supporting MTC UE class for coverage extension andservice enhancement and the eNB configures the data size suitable forthe MTC UE so as to avoid malfunction of the MTC UE and secure broadcoverage of the UE using an MTC-specific transmission scheme.

While the present disclosure has been shown and described with referenceto various embodiments thereof, it will be understood by those skilledin the art that various changes in form and details may be made thereinwithout departing from the spirit and scope of the present disclosure asdefined by the appended claims and their equivalents.

What is claimed is:
 1. A method performed by a terminal in a wirelesscommunication system, the method comprising: receiving a first messageincluding system information from a base station associated with a cell;determining whether the system information includes allowanceinformation indicating that a category 0 terminal is allowed to accessthe cell; barring a selection of the cell, in case that the systeminformation does not include the allowance information; transmitting arandom access preamble to the base station, in case that the systeminformation includes the allowance information; receiving a randomaccess response (RAR) message from the base station as a response to therandom access preamble; transmitting a second message for requesting anestablishment of radio resource control (RRC) connection on commoncontrol channel (CCCH) to the base station as a response to the RARmessage; and receiving a third message for establishing the RRCconnection as a response to the second message, wherein informationindicating that the CCCH is for the category 0 terminal is transmittedwith the second message to the base station, and wherein the category 0terminal is characterized as having a maximum data rate of 1000 bitswithin a subframe.
 2. The method of claim 1, wherein the first messagecomprises a system information block (SIB).
 3. The method of claim 1,wherein the information indicating that the CCCH is for the category 0terminal is contained in a medium access control (MAC) header.
 4. Themethod of claim 1, wherein the information indicating that the CCCH isfor the category 0 terminal includes a logical channel identifier (LCID)set to a determined value and the determined value is different from00000.
 5. The method of claim 1, wherein the third message is receivedas fragmented form of the third message or removed form of part of thethird message.
 6. A terminal in a wireless communication system, theterminal comprising: a transceiver; and a controller configured to:control the transceiver to receive a first message including systeminformation from a base station associated with a cell, determinewhether the system information includes allowance information indicatingthat a category 0 terminal is allowed to access the cell, bar aselection of the cell, in case that the system information does notinclude the allowance information, control the transceiver to transmit arandom access preamble to the base station, in case that the systeminformation includes the allowance information, control the transceiverto receive a random access response (RAR) message from the base stationas a response to the random access preamble, control the transceiver totransmit a second message for requesting an establishment of radioresource control (RRC) connection on common control channel (CCCH) tothe base station as a response to the RAR message, and control thetransceiver to receive a third message for establishing the RRCconnection as a response to the second message, wherein informationindicating that the CCCH is for the category 0 terminal is transmittedwith the second message to the base station, and wherein the category 0terminal is characterized as having a maximum data rate of 1000 bitswithin a subframe.
 7. The terminal of claim 6, wherein the first messagecomprises a system information block (SIB).
 8. The terminal of claim 6,wherein the information indicating that the CCCH is for the category 0terminal is contained in a medium access control (MAC) header.
 9. Theterminal of claim 6, wherein the information indicating that the CCCH isfor the category 0 terminal includes a logical channel identifier (LCID)set to a determined value and the determined value is different from00000.
 10. The terminal of claim 6, wherein the third message isreceived as fragmented form of the third message or removed form of partof the third message.
 11. A method performed by a base station in awireless communication system, the method comprising: determiningwhether to allow an access of a category 0 terminal to a cell associatedwith the base station; generating a first message including allowanceinformation indicating that the category 0 terminal is allowed to accessto the cell, in case that the base station allows the access of thecategory 0 terminal to the cell; broadcasting the first message;receiving a random access preamble from a terminal; transmitting arandom access response (RAR) message for the terminal as a response tothe random access preamble; receiving, from the terminal, a secondmessage for requesting an establishment of radio resource control (RRC)connection on common control channel (CCCH) as a response to the RARmessage, the second message including information indicating that theCCCH is for the category 0 terminal; identifying that the terminal isthe category 0 terminal based on the information indicating that theCCCH is for the category 0 terminal; and transmitting, to the terminal,a third message for establishing the RRC connection as a response to thesecond message, wherein the category 0 terminal is characterized ashaving a maximum data rate of 1000 bits within a subframe.
 12. Themethod of claim 11, wherein the first message comprises a systeminformation block (SIB).
 13. The method of claim 11, wherein theinformation indicating that the CCCH is for category 0 terminal iscontained in a medium access control (MAC) header.
 14. The method ofclaim 11, wherein the information indicating that the CCCH is for thecategory 0 terminal includes a logical channel identifier (LCID) set toa determined value and the determined value is different from
 00000. 15.A base station in a wireless communication system, the base stationcomprising: a transceiver; and a controller configured to: determinewhether to allow an access of a category 0 terminal to a cell associatedwith the base station, generate a first message including allowanceinformation indicating that the category 0 terminal is allowed to accessthe cell, in case that the base station allows the access of thecategory 0 terminal to the cell, control the transceiver to broadcastthe first message, control the transceiver to receive a random accesspreamble from a terminal, control the transceiver to transmit a randomaccess response (RAR) message for the terminal as a response to therandom access preamble, control the transceiver to receive, from theterminal, a second message for requesting an establishment of radioresource control (RRC) connection on common control channel (CCCH) as aresponse to the RAR message, the second message including informationindicating that the CCCH is for the category 0 terminal, identify thatthe terminal is the category 0 terminal based on information indicatingthat the CCCH is for the category 0 terminal, and control thetransceiver to transmit, to the terminal, a third message forestablishing the RRC connection as a response to the second message,wherein the category 0 terminal is characterized as having a maximumdata rate of 1000 bits within a subframe.
 16. The base station of claim15, wherein the first message comprises a system information block(SIB).
 17. The base station of claim 15, wherein the informationindicating that the CCCH is for the category 0 terminal is contained ina medium access control (MAC) header.
 18. The base station of claim 15,wherein the information indicating that the CCCH is for the category 0terminal includes a logical channel identifier (LCID) set to adetermined value and the determined value is different from 00000.